General Description: 6 note polyphonic. Three 6-stage envelope generators. Two oscillators, each can output up to 4 square waves simultaneously. The filter section is switchable between polyphonic & mono modes. Programmable midi automation, midi learn for all parameters, patch library.

The XS-4 attempts to reproduce the sound a group of similar analog synths which appeared in the mid 80’s. Examples are the Korg Poly 800, Siel DK-80 and Suzuki SX-500. These instruments have a very similar architecture, but do not have identical sonic characteristics.The oscillators, typically built around chips designed to power organs, do sound very nice when run through an analog filter and a punchy set of envelopes - we felt this was a sound well worth emulating.The result is the XS-4, and were broadly happy with its performance. Regrettably, it’s rather power hungry (CPU usage) because the oscillators are outputting 8 waveforms per note and the filter / envelope stages are also now very CPU intensive. Selecting monophnic filter mode may eleviate the issue somewhat. However, pitch modulation will place a particularly high load on the CPU, as will long loudness decay times.Despite this, we feel that sonically, the instrument has considerable merit; you can assess it yourself, within minutes, by downloading the demo from the link below.

Audio Demo - all sounds from the XS-4, (external effects applied)Please refer to the MM-2 audio demo description since this one was produced in a similar way.